NOAA seem hell bent on dropping the knot as a basic measure despite
its ideal meter. So here goes with the conversion tables once mo

Saffir-Simpson Scale

Category One Hurricane: 64-82 knots,
74-95 mph,or 119-153 km/hr.

Category Two Hurricane: 83-95 knots;
96-110 mph, or 154-177 km/hr.

Category Three Hurricane: 96-113 knots;
111-130 mph, or 178-209 km/hr.

Category Four Hurricane: 114-135 knots;
131-155 mph, or 210-249 km/hr.

Category Five Hurricane:
Winds greater than 135 knots;
155 mph, or 249 km/hr.

http://www.nhc.noaa.gov/aboutsshs.shtml

THE BEAUFORT WIND SCALE

Force miles/hour knots description

0 0-1 0-1 Calm Sea like a mirror

1 1-3 1-3 Light air Ripples with the appearance of scales are formed,
but without foam crests.

2 4-7 4-6 Light Breeze Small wavelets, still short, but more
pronounced. Crests have a glassy appearance and do not break.

3 8-12 7-10 Gentle Breeze Large wavelets. Crests begin to break. Foam
of glassy appearance. Perhaps scattered white horses.

4 13-18 11-16 Moderate Breeze Small waves, becoming larger; fairly
frequent white horses.

5 19-24 17-21 Fresh Breeze Moderate waves, taking a more pronounced
long form; many white horses are formed. Chance of some spray.

6 25-31 22-27 Strong Breeze Large waves begin to form; the white foam
crests are more extensive everywhere. Probably some spray.

7 32-38 28-33 Near Gale Sea heaps up and white foam from breaking
waves begins to be blown in streaks along the direction of the wind.

8 39-46 34-40 Gale Moderately high waves of greater length; edges of
crests begin to breakinto spindrift. The foam is blown in well-marked
streaks along the direction of the wind.

9 47-54 41-47 Severe Gale High waves. Dense streaks of foam along the
direction of the wind. Crests of waves begin to topple, tumble and
roll over. Spray may affect visibility.

10 55-63 48-55 Storm Very high waves with long over-hanging crests.
The resulting foam, in great patches, is blown in dense white streaks
along the direction of the wind. On the whole the surface of the sea
takes on a white appearance. The 'tumbling' of the sea becomes heavy
and shock-like. Visibility affected.

11 64-72 56-63 Violent Storm Exceptionally high waves (small and
medium-size ships might be for a time lost to view behind the waves).
The sea is completely covered with long white patches of foam lying
along the direction of the wind. Everywhere the edges of the wave
crests are blown into froth. Visibility affected.

12 73-83 64-71 Hurricane The air is filled with foam and spray. Sea
completely white with driving spray; visibility very seriously
affected.

The Beaufort scale was extended in 1944, when Forces 13 to 17 were
added. Hitherto, Force 12 (Hurricane) had been the highest point on
the scale, referring to a sustained wind speed of 64 knots (32.7 m/s)
or more - that is, the wind speed averaged over a period of 10
minutes.

The additional five points extended the scale to 118 knots (61.2 m/s),
with Force 12 referring only to speeds in the range 64 to 71 knots
(32.7-36.9 m/s). However, Forces 13 to 17 were intended to apply only
to special cases, such as tropical cyclones. They were not intended
for ordinary use at sea - indeed, it's impossible to judge Forces 13
to 17 by the appearance of the sea. For all normal purposes, the
Beaufort scale extends from Force 0 (Calm) to Force 12 (Hurricane),
with Force 12 defined as a sustained wind of 64 knots (32.7 m/s) or
more.


One of the first scales to estimate wind speeds and the effects was
created by Britain's Admiral Sir Francis Beaufort (1774-1857). He
developed the scale in 1805 to help sailors estimate the winds via
visual observations. The scale starts with 0 and goes to a force of
12.

The Beaufort scale is still used today to estimate wind strengths.

BEAUFORT SCALE: Specifications and equivalent speeds for use on land

FORCE EQUIVALENT SPEED DESCRIPTION SPECIFICATIONS FOR USE ON LAND
10 m above ground
miles/hour knots0 0-1 0-1 Calm Calm; smoke rises
vertically.

1 1-3 1-3 Light air Direction of wind shown by smoke drift, but not by
wind vanes.

2 4-7 4-6 Light Breeze Wind felt on face; leaves rustle; ordinary
vanes moved by wind.

3 8-12 7-10 Gentle Breeze Leaves and small twigs in constant motion;
wind extends light flag.

4 13-18 11-16 Moderate Breeze Raises dust and loose paper; small
branches are moved.

5 19-24 17-21 Fresh Breeze Small trees in leaf begin to sway; crested
wavelets form on inland waters.

6 25-31 22-27 Strong Breeze Large branches in motion; whistling heard
in telegraph wires; umbrellas used with difficulty.

http://www.metoffice.gov.uk/educatio.../beaufort.html

The Dvorak technique (developed in 1974 by Vernon Dvorak) is a widely
used system to subjectively estimate tropical cyclone intensity based
solely on visible and infrared satellite images. Several agencies
issue Dvorak intensity numbers for cyclones of sufficient intensity.
These include the National Hurricane Center's Tropical Analysis and
Forecast Branch (TAFB), the NOAA/NESDIS Satellite Analysis Branch
(SAB), the Joint Typhoon Warning Center at the Naval Pacific
Meteorology and Oceanography Center in Pearl Harbor, Hawaii, and the
Air Force Weather Agency (AFWA).

In a developing cyclone, the technique takes advantage of the fact
that cyclones of similar intensity tend to have certain characteristic
features, and as they strengthen, they tend to change in appearance in
a predictable manner. The structure and organization of the tropical
cyclone are tracked over 24 hours to determine if the storm has
weakened, maintained its intensity, or strengthened. Various central
cloud and banding features are compared with templates that show
typical storm patterns and their associated intensity.

If infrared satellite imagery is available for a cyclone with a
visible eye pattern, then the technique utilizes the difference
between the temperature of the warm eye and the surrounding cold cloud
tops to determine intensity (colder cloud tops generally indicate a
more intense storm). In each case a "T-number" and a Current Intensity
(CI) value are assigned to the storm. These measurements range between
1 (minimum intensity) and 8 (maximum intensity). The T-number and CI
value are the same except for weakening storms, in which case the CI
is higher.


Number Knots Pressure Millibars
Atlantic NW Pacific
1.0 25 ---- ----
2.0 30 1009 1000
2.5 35 1005 997
3.0 45 1000 991
3.5 55 994 984
4.0 65 987 976
4.5 77 979 966
5.0 90 970 954
5.5 102 960 941
6.0 115 948 927
6.5 127 935 914
7.0 140 921 898
7.5 155 906 879
8.0 170 890 858

The National Hurricane Center will often quote Dvorak T-numbers e.g.

DVORAK SATELLITE INTENSITY ESTIMATE OF T2.5/35 KT.

The Cooperative Institute for Meteorological Satellite Studies (CIMSS)
at the University of Wisconsin-Madison has developed the Objective
Dvorak Technique (ODT). This is a modified version of the Dvorak
technique which uses computer algorithms rather than subjective human
interpretation to arrive at a CI number. This is generally not
implemented for tropical depressions or weak tropical storms.

http://en.wikipedia.org/wiki/Dvorak_technique

If we had dropped the Statute mile in favour of the knot in thr 1970's
rather than adopt the silly European ideal, then the world would have
been a better place.

We'd still have coins with the heads of several monarchs, we'd have
our own iron and steel production facilities and maybe even kept a
motor car and motorcycle industry. (No great loss there, I have to
admit.)

We would have been able to steer the USA away from its global cabals
and we would be able to say to monsters like China that they must stop
genocidal mania in all its forms just as we did in India and the rest
of Asia when we had the remit to do so.

Or not, as the case may be.